1. Field of the Invention
The present invention concerns clutches incorporating two friction disks, of both the "dual clutch" type with two outputs in which each friction disk is keyed against rotation on a separate driven shaft, and the single-output "two-plate" clutch in which both friction disks are keyed against rotation on the same driven shaft.
The invention is more particularly concerned with the mechanism for such a clutch, that is to say with the component parts which, including a friction disk, are assembled, in practice in the form of a self-contained unit, on a reaction plate (or flywheel) with an interposed friction disk.
Such a clutch mechanism, for which a particular application is to automotive vehicles, generally comprises a first plate, hereinafter referred to as the reaction plate, and, on the same side of said reaction plate and movable axially relative thereto, a friction disk and two other plates, hereinafter referred to as pressure plates. The side of the reaction plate referred to is that on which the mechanism is mounted on a second reaction plate or flywheel. Respective annular springs act continuously on said pressure plates so as to urge one towards the reaction plate, to clamp the friction disk, and the other in the opposite direction.
The invention is more particularly concerned with mechanisms in which these annular springs are of the Belleville type, conjointly bearing on an annular spacer which is keyed against relative motion relative to the reaction plate.
2. Description of the Prior Art
This type of clutch mechanism is disclosed in U.S. Pat. No. 3,021,931. The clutch mechanism disclosed in French patent application No. 77 21605 published under No. 2 397 563 is also of this type.
In U.S. Pat. No. 3,021,931 the annular spacer on which the annular springs bear is an annular member forming part of a skirt by virtue of which the reaction plate defines the volume within which the pressure plates move. Consequently the skirt is not of unitary construction and is of considerable thickness.
As a result the assembly is somewhat complicated and relatively large in the axial direction.
In French Pat. No. 2 397 563 the annular spacer on which the annular springs bear is a simple ring separate from the reaction plate and freely engaged in the skirt of the latter. Consequently the skirt may be of unitary construction. The ring is stacked axially with the annular springs, between the latter, and keyed against axial movement relative to the reaction plate through one of the annular springs, by virtue of the latter bearing on a transversely disposed shoulder on the skirt of the reaction plate.
Although this arrangement is satisfactory, it has the disadvantage that it is not suited to the standardized manufacture of clutch mechanisms of the same basic type but with different characteristics, in particular clutch mechanisms fitted with annular springs of different thicknesses.
In these clutch mechanisms, the height of the stack formed by the annular springs and the ring separating them is strictly limited by the shoulder on which one of the annular springs bears and by segments projecting radially from the reaction plate skirt, disposed opposite the shoulder on the latter and retaining the other annular spring.
Thus if it is required to fit thicker annular springs, the thickness of the ring separating them must be reduced.
This ring must have at least a defined minimum thickness to permit appropriate action of the annular springs on changing from the engaged to the disengaged configuration of the clutch, however.
This therefore imposes a limit on the range of thicknesses which may be used for the annular springs.
The object of the present invention is to provide an arrangement which overcomes these disadvantages and which thus favors standardized manufacture.